High Temperature Control in Mediterranean Greenhouse Production: The Constraints and the Options

Abstract

In the open field, the environment is a critical determinant of crop yield and produce quality and it affects the geographical distribution of most crop species. In contrast, in protected cultivation, environmental control allows the fulfillment of the actual needs depending on the technological level. The economic optimum, however, depends on the trade-off between the costs of increased greenhouse control and increase in return, dictated by yield quantity, yield quality and production timing. Additional constraints are increasingly applied for achieving environmental targets. However, the diverse facets of greenhouse technology in different areas of the world will necessarily require different approaches to achieve an improved utilization of the available resources. Although advanced technologies to improve resource use efficiency can be developed as a joint effort between different players involved in greenhouse technology, some specific requirements may clearly hinder the development of common "European" resource management models that, conversely should be calibrated for different environments. For instance, the quantification and control of resource fluxes can be better accomplished in a relatively closed and fully automated system, such as those utilized in the glasshouse of Northern-Central Europe, compared to Southern Europe, where different typologies of semiopen/semi-closed greenhouse systems generally co-exist. Based on these considerations, innovations aimed at improving resource use efficiency in greenhouse agriculture should implement these aspects and should reinforce and integrate information obtained from different research areas concerning the greenhouse production. Advancing knowledge on the physiology of high temperature adaptation, for instance, may support the development and validation of models for optimizing the greenhouse system and climate management in the Mediterranean. Overall, a successful approach will see horticulturists, plant physiologists, engineers and economists working together toward the definition of a sustainable greenhouse system.

An overview of climate and crop yield in closed greenhouses

“…Therefore it makes sense that, in research, attention is paid to well-functioning technical systems that provide optimal climate conditions. Regional differences in climate are important and the equipment should adapt to deliver the optimal climate conditions (Vanthoor, 2011;De Pascale and Stanghellini, 2011).…”

Smart greenhouse covers: a look into the future

“…In mild winter climate regions, greenhouses are often located close to the sea where air humidity and temperature are normally near optimum for growing most vegetable crops and greenhouse climate can be acceptable during most of the growing season provided that enough natural ventilation capacity is available. Unfortunately, this is hardly the case in these areas, represented by the Mediterranean region (Montero et al, 1985;De Pascale and Stanghellini, 2011;Fernańdez et al, 2018). This leads growers to use shading to try to lower these high temperatures.…”

“…Whitewash can greatly decrease the canopy to air temperature difference in relation to a non-whitewashed greenhouse, decreasing transpiration and improving water use efficiency (Baille et al, 2001;Mashonjowa et al, 2010;Gazquez et al, 2006). Total yield can be affected due to the decrease in intercepted PAR by the crop (De Pascale and Stanghellini, 2011) under Mediterranean summer conditions. However, marketable yield can benefit from shading (Gazquez et al, 2006) due to lower incidence of fruit physiological problems (e.g., BER or cracking) and higher fruit homogeneity (Briassoulis et al, 2007).…”

Application of the Climograph for the Greenhouse Plan of Subtropical and Tropical Regions

“…Fitz-Rodriguez et al [13] used a climograph that plotted the average photosynthetic photon flux versus average daily air temperature for every month of four locations to demonstrate the dynamic models of greenhouse environments. De Pascale and Stanghellini [14] described a climograph by plotting the mean temperature in the X-axis and mean solar radiation in the Y-axis for the Netherlands and South Italy. They discussed the requirement of climatic controls for greenhouse vegetable crop cultivation based on different controlling techniques such as closed and continuously ventilated, heating at night/day, heating night, and no heating.…”

“…Climographs have been used by researchers. Most of the reports have concerned the relationship between the mean radiation and mean monthly air temperature [10][11][12][13][14][15][16][17]. Climographs obtained by plotting the mean monthly minimum and maximum air temperature were only reported by Kittas [12] and Zabeltitz [10].…”